CVE-2026-4671
Denial-of-service via crafted CSS selectors/linkification in justhtml <1.18.0
Is CVE-2026-4671 being exploited?
Not confirmed. CVE-2026-4671 does not appear in CISA's Known Exploited Vulnerabilities catalog, which records only exploitation that has been observed and reported publicly. That is evidence of absence of a report, not evidence the flaw is unattacked. EPSS currently estimates a 0.37% probability of exploitation in the next 30 days.
How severe is CVE-2026-4671?
CVE-2026-4671 is rated High with a CVSS score of 8.7. Severity describes how bad exploitation would be, not how likely it is: pair it with exploitation evidence before deciding what to patch first.
Is there a patch for CVE-2026-4671?
Yes. A fix has been recorded for CVE-2026-4671. The vendor advisory is the authority on the exact fixed version — apply it from there rather than from a summary.
What does CVE-2026-4671 affect?
CVE-2026-4671 affects justhtml <1.18.0, Web apps using justhtml query()/matches()/selector transforms, Apps performing linkification on untrusted text. Confirm the exact affected versions against the vendor advisory before deciding you are exposed.
What should I do about CVE-2026-4671?
Upgrade to justhtml 1.18.0; validate/limit untrusted selectors and linkify inputs
Exploitation status reflects CISA's KEV catalog as we last synced it. Check the catalog directly.
Remote denial-of-service: crafted selectors or linkification input can exhaust CPU/memory, causing app availability loss.
Patch when possible
- affected< 1.18.0
As published in the CVE Program record. A version outside these ranges is not a statement that it is unaffected — vendors sometimes understate a range, and distribution-backported builds carry upstream numbers that do not reflect what was patched into them.